New amd gpu won't start monitor

[eatonre]

So I recently bought a AMD rx 480 x, but I'm having a problem which is that it wont give signal to my monitor. Everything is being powered also the gpu, but no signal to my monitor(I can actually go on teamviewer and acces the desktop). I installed it correctly, had a nvidea 660N before and if I replace my old gpu with the new one the monitor gets a signal. Also my mobo has no intergrated graphics (ASROCK 990FX extreme3). What I'm guessing is that I need a new PSU. Current one is SeaSonic M12II EVO 520. If someone has a clue what I need to do please help me.

 

[WyomingKnott]

Could the new card be defective? That's what "New card don't work, system works fine with old card" sounds like.
First, try booting into Safe Mode with the new card. When you change cards, you should ideally
1) Uninstall the old drivers
2) Change cards
3) Boot into safe mode and install the new drivers.

So try booting to safe mode (instructions will depend on OS version and your computer) and, if there is a low-res display, installing the proper drivers. Silly question, but did you attach the extra power cable to the card? That card can draw 150 watts, and requires a pci-e power connector.

There was also a problem with that card drawing too much power until updated drivers were installed.

 

[eatonre]

Could the new card be defective? That's what "New card don't work, system works fine with old card" sounds like.
First, try booting into Safe Mode with the new card. When you change cards, you should ideally
1) Uninstall the old drivers
2) Change cards
3) Boot into safe mode and install the new drivers.

So try booting to safe mode (instructions will depend on OS version and your computer) and, if there is a low-res display, installing the proper drivers. Silly question, but did you attach the extra power cable to the card? That card can draw 150 watts, and requires a pci-e power connector.

There was also a problem with that card drawing too much power until updated drivers were installed.

Thank you for your fast reply.
The new gpu is not defective, already tested on a different pc. I've already uninstalled all old drivers and installed the AMD drivers. Also I did not attach a extra power cable, I dont understand why I should since the one that is attached is a 6+2 pin.

 

[WyomingKnott]

The 6+2 pin IS the extra power cable. Up to 75 watts, the cards don't use a cable and draw power from the bus. Some folks forget to connect the cable.

Given that the drivers are current and the card works in another machine, I have no idea. Sorry.